1. Field of the Invention
The present invention relates to applications of resource sharing among multiple channel signals via wavefront (WF) multiplex (mux) and de-multiplex (demux) techniques. More specifically, the present invention discloses methods and applications for sharing a bank of power amplifiers (PAs) for many independent signals via wavefront multiplexing and demuxing techniques. The increased flexibility of multiple-parallel PAs allowing increased design flexibility is but one of the many advantages of the present invention.
2. Description of Related Art
In the satellite communications industry, in-phase power combiners have been used extensively to coherently combine multiple amplifiers in order to gain enhanced power output [1]. However, these power combiners only work at a given frequency, thus limiting their flexibility when applications require such versatility. Additionally, there are satellite payload designs featuring RF power sharing among downlink spot beams that exhibit large disparities in traffic patterns [2]. This invention presents a smart and dynamic power amplifier module that features both power sharing and power combining capabilities.
WF muxing/demuxing techniques are powerful tools for path length equalizations among parallel paths/channels. SDS has applied these techniques for various applications; (1) Wireless power combining from multiple transponders from the same satellites and/or different transponding satellites [3], (2) back channel equalization for ground based beam forming process in satellite applications [4], (3) Distributed data storage [5], and (4) efficient accessing communications satellites by polarization-incompatible terminals [7].
Uniqueness Structures of the OWFDM for Power Amplifications
Our proposed OWFDM techniques will coherently spread an input signal into multiple channels with a unique phase distribution pattern, referred to as a wavefront (WF). An N-channel WF multiplexing (mux) processor can spread N independent signals into a bank of N parallel PAs. As a result, each of the input signals are concurrently propagating in multiple channels and are amplified by N individual PAs in a form of orthogonal signal structure in the selected N-dimensional domain. The generated orthogonality is among multiple wave-fronts (WFs). With N parallel propagating channels, there are N-orthogonal WFs available. Probing signal streams may be attached to one of them. The remaining WFs are available for various input signals.
Amplified signals originated from various input ports through various PAs arriving at a destination feature differential phase delays, Doppler drifts, and amplitude amplifications/attenuations. A post-amplification processing will be designed to equalize the differential phase delays among propagation paths, and differential amplifications among the PAs. Calibrations and equalizations may take advantage of embedded probe signals and iterative optimization loops. As a result of equalizations, the WFs become spatially orthogonal and the attached amplified signals can then be precisely reconstituted by a WF demuxer implemented by a RF Butler matrix.